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Was Sarah Abraham's Sister?
It is commonly believed by many that Sarah was Abraham's half-sister, due to what is written in Genesis 20:12, when Abraham said "And yet indeed she is my sister; she is the daughter of my father, but not the daughter of my mother; and she became my wife." but as we will see below with other examples in Scripture, this isn't the case as it seems, as the terms "brother", "sister", "son", as well as "father" can refer to more in Hebrew, than in English. Below, let's begin in Genesis 12, where GOD gives the promise unto Abram/Abraham.
Genesis 12:1-3
1 Now the LORD had said unto Abram, Get thee out of thy country, and from thy kindred, and from thy father’s house, unto a land that I will shew thee:
Abraham was called Abram before GOD changed his name.
2 and I will make of thee a great nation, and I will bless thee, and make thy name great; and thou shalt be a blessing:
3 and I will bless them that bless thee, and curse him that curseth thee: and in thee shall all families of the earth be blessed.
As we can see, GOD was very pleased with Abraham and the life he lived, and even promised to make a great nation out of him. In Genesis 22:17, GOD told him that his offspring would be as numerous as the stars and the sand of the sea. However, in Deuteronomy 27:22, Scripture says "Cursed be he that lieth with his sister, the daughter of his father, or the daughter of his mother. And all the people shall say, Amen." Now are we supposed to believe that GOD contradicted HIMself by blessing Abraham abundantly who supposedly married his sister, which GOD instructed the one who does would be cursed? How silly. In Malachi 3:6, GOD says "For I am the LORD, I change not; therefore ye sons of Jacob are not consumed." And so it is. Below, let's look at some examples for the words "brother", "sister", and "father", and we'll see that they have more meanings in the Hebrew language, than they do in our English language.
Abraham was called Abram before GOD changed his name.
2 and I will make of thee a great nation, and I will bless thee, and make thy name great; and thou shalt be a blessing:
3 and I will bless them that bless thee, and curse him that curseth thee: and in thee shall all families of the earth be blessed.
As we can see, GOD was very pleased with Abraham and the life he lived, and even promised to make a great nation out of him. In Genesis 22:17, GOD told him that his offspring would be as numerous as the stars and the sand of the sea. However, in Deuteronomy 27:22, Scripture says "Cursed be he that lieth with his sister, the daughter of his father, or the daughter of his mother. And all the people shall say, Amen." Now are we supposed to believe that GOD contradicted HIMself by blessing Abraham abundantly who supposedly married his sister, which GOD instructed the one who does would be cursed? How silly. In Malachi 3:6, GOD says "For I am the LORD, I change not; therefore ye sons of Jacob are not consumed." And so it is. Below, let's look at some examples for the words "brother", "sister", and "father", and we'll see that they have more meanings in the Hebrew language, than they do in our English language.
Genesis 14:12-16
12 And they took Lot, Abram’s brother’s son, who dwelt in Sodom, and his goods, and departed.
As we can see, Abraham was Lot's uncle, as he was his brother's son, but in verse 14 below, Lot is referred to as his "brother". It should be noted that "brother" (= ʼâch) in the Hebrew, depending on the context of the chapter it comes from, can simply mean "kindred", and not always one's literal brother as we refer to today.
13 And there came one that had escaped, and told Abram the Hebrew; for he dwelt in the plain of Mamre the Amorite, brother of Eshcol, and brother of Aner: and these were confederate with Abram.
14 And when Abram heard that his brother was taken captive, he armed his trained servants, born in his own house, three hundred and eighteen, and pursued them unto Dan.
15 And he divided himself against them, he and his servants, by night, and smote them, and pursued them unto Hobah, which is on the left hand of Damascus.
16 And he brought back all the goods, and also brought again his brother Lot, and his goods, and the women also, and the people.
Continuing, we'll see the same applies in Genesis 29 with Laban and Jacob.
As we can see, Abraham was Lot's uncle, as he was his brother's son, but in verse 14 below, Lot is referred to as his "brother". It should be noted that "brother" (= ʼâch) in the Hebrew, depending on the context of the chapter it comes from, can simply mean "kindred", and not always one's literal brother as we refer to today.
13 And there came one that had escaped, and told Abram the Hebrew; for he dwelt in the plain of Mamre the Amorite, brother of Eshcol, and brother of Aner: and these were confederate with Abram.
14 And when Abram heard that his brother was taken captive, he armed his trained servants, born in his own house, three hundred and eighteen, and pursued them unto Dan.
15 And he divided himself against them, he and his servants, by night, and smote them, and pursued them unto Hobah, which is on the left hand of Damascus.
16 And he brought back all the goods, and also brought again his brother Lot, and his goods, and the women also, and the people.
Continuing, we'll see the same applies in Genesis 29 with Laban and Jacob.
Genesis 29:10-15
10 And it came to pass, when Jacob saw Rachel the daughter of Laban his mother’s brother, and the sheep of Laban his mother’s brother, that Jacob went near, and rolled the stone from the well’s mouth, and watered the flock of Laban his mother’s brother.
Here it is perfectly clear that Laban is Jacob's uncle, but below we'll see they refer to each other as "brother" as translated into the English (KJV), which is because again, brother (= ʼâch) in the Hebrew can simply be used when referring to generalized kinship (i.e. family), just as we will see later with the term "sister" (= ʼâchôwth), which is the feminine form of (ʼâch).
11 And Jacob kissed Rachel, and lifted up his voice, and wept.
12 And Jacob told Rachel that he was her father’s brother, and that he was Rebekah’s son: and she ran and told her father.
13 And it came to pass, when Laban heard the tidings of Jacob his sister’s son, that he ran to meet him, and embraced him, and kissed him, and brought him to his house. And he told Laban all these things.
14 And Laban said to him, Surely thou art my bone and my flesh. And he abode with him the space of a month.
15 And Laban said unto Jacob, Because thou art my brother, shouldest thou therefore serve me for nought? tell me, what shall thy wages be?
In the next example, we'll see where the same applies with the word "father".
Here it is perfectly clear that Laban is Jacob's uncle, but below we'll see they refer to each other as "brother" as translated into the English (KJV), which is because again, brother (= ʼâch) in the Hebrew can simply be used when referring to generalized kinship (i.e. family), just as we will see later with the term "sister" (= ʼâchôwth), which is the feminine form of (ʼâch).
11 And Jacob kissed Rachel, and lifted up his voice, and wept.
12 And Jacob told Rachel that he was her father’s brother, and that he was Rebekah’s son: and she ran and told her father.
13 And it came to pass, when Laban heard the tidings of Jacob his sister’s son, that he ran to meet him, and embraced him, and kissed him, and brought him to his house. And he told Laban all these things.
14 And Laban said to him, Surely thou art my bone and my flesh. And he abode with him the space of a month.
15 And Laban said unto Jacob, Because thou art my brother, shouldest thou therefore serve me for nought? tell me, what shall thy wages be?
In the next example, we'll see where the same applies with the word "father".
John 8:37-39
37 I know that ye are Abraham’s seed; but ye seek to kill me, because my word hath no place in you.
Here JESUS is talking to some of the descendants of Abraham, who were biologically of the offspring of Abraham, but were not spiritually children of Abraham, as Abraham obeyed GOD and recognized GOD, whereas these wicked ones here couldn't recognize, neither believed who JESUS/EMMANUEL (= with us is GOD) was/is.
38 I speak that which I have seen with my Father: and ye do that which ye have seen with your father.
Here JESUS is speaking spiritually.
39 They answered and said unto him, Abraham is our father. Jesus saith unto them, If ye were Abraham’s children, ye would do the works of Abraham.
JESUS wasn't contradicting HIMself here, but again is speaking in the spiritual sense. Galatians 3:7 says "Know ye therefore that they which are of faith, the same are the children of Abraham." Now aside from this, notice they refer to Abraham as their "father" even though Abraham clearly was not their father as he had been dead for over a thousand years, but the point of reviewing this, is that the word "father", even in the Old Testament (Hebrew), can refer to a forefather, not always one's dad. In Daniel 5, Nebuchadnezzar is referred to as king Belshazzar's "father" in verses 2, 11, 13, 18, and verse 22, although Nebuchadnezzar was technically his "grandfather"; the reason for this is because in the Bible, there are no words in the original languages (Hebrew & Chaldee [Old Testament] or Greek [New Testament) for "grandfather", "grandson, or great-grandfather", etc. The same applies in 2 Kings 2:12 too, as Elisha called Elijah his father, as the word "father" isn't always directed in the literal sense but sometimes figuratively. Another example can be found in Matthew 1:1, as JESUS is called the "son of David", and in Genesis 32:9, "And Jacob said, O God of my father Abraham, and God of my father Isaac, the LORD which saidst unto me, Return unto thy country, and to thy kindred, and I will deal well with thee:"
So as we can clearly see, which you can check out for yourself using a good Hebrew concordance of the Bible such as the Strong's Exhaustive, words like "brother", "father", and even "sister", as we will see, do not always imply a literal relationship, but can simply be used figuratively, or to describe a forefather connection, or a well thought of relative.
Continuing, let's turn to Genesis 26.
Here JESUS is talking to some of the descendants of Abraham, who were biologically of the offspring of Abraham, but were not spiritually children of Abraham, as Abraham obeyed GOD and recognized GOD, whereas these wicked ones here couldn't recognize, neither believed who JESUS/EMMANUEL (= with us is GOD) was/is.
38 I speak that which I have seen with my Father: and ye do that which ye have seen with your father.
Here JESUS is speaking spiritually.
39 They answered and said unto him, Abraham is our father. Jesus saith unto them, If ye were Abraham’s children, ye would do the works of Abraham.
JESUS wasn't contradicting HIMself here, but again is speaking in the spiritual sense. Galatians 3:7 says "Know ye therefore that they which are of faith, the same are the children of Abraham." Now aside from this, notice they refer to Abraham as their "father" even though Abraham clearly was not their father as he had been dead for over a thousand years, but the point of reviewing this, is that the word "father", even in the Old Testament (Hebrew), can refer to a forefather, not always one's dad. In Daniel 5, Nebuchadnezzar is referred to as king Belshazzar's "father" in verses 2, 11, 13, 18, and verse 22, although Nebuchadnezzar was technically his "grandfather"; the reason for this is because in the Bible, there are no words in the original languages (Hebrew & Chaldee [Old Testament] or Greek [New Testament) for "grandfather", "grandson, or great-grandfather", etc. The same applies in 2 Kings 2:12 too, as Elisha called Elijah his father, as the word "father" isn't always directed in the literal sense but sometimes figuratively. Another example can be found in Matthew 1:1, as JESUS is called the "son of David", and in Genesis 32:9, "And Jacob said, O God of my father Abraham, and God of my father Isaac, the LORD which saidst unto me, Return unto thy country, and to thy kindred, and I will deal well with thee:"
So as we can clearly see, which you can check out for yourself using a good Hebrew concordance of the Bible such as the Strong's Exhaustive, words like "brother", "father", and even "sister", as we will see, do not always imply a literal relationship, but can simply be used figuratively, or to describe a forefather connection, or a well thought of relative.
Continuing, let's turn to Genesis 26.
Genesis 26:1-9
1 And there was a famine in the land, beside the first famine that was in the days of Abraham. And Isaac went unto Abimelech king of the Philistines unto Gerar.
2 And the LORD appeared unto him, and said, Go not down into Egypt; dwell in the land which I shall tell thee of:
3 sojourn in this land, and I will be with thee, and will bless thee; for unto thee, and unto thy seed, I will give all these countries, and I will perform the oath which I sware unto Abraham thy father;
4 and I will make thy seed to multiply as the stars of heaven, and will give unto thy seed all these countries; and in thy seed shall all the nations of the earth be blessed;
5 Because that Abraham obeyed my voice, and kept my charge, my commandments, my statutes, and my laws.
Here we have documentation that Abraham obeyed GOD, and kept his charge, commandments, statutes, and laws. This word "commandments" is "mitsvâh" in the Hebrew, which is even the same word used for the Commandments that GOD gave to Moses. GOD even tells us in Deuteronomy 28, starting in verse 15, of all the curses that would come upon the people who did not keep all of HIS commandments, and as we can see, Abraham kept them by obeying GOD and striving to do what is right, as well as many of Adam's descendants, which means they would have known right from wrong, righteousness from unrighteousness, sin from non-sin, and again as mentioned earlier, GOD says in Deuteronomy 27:22, GOD says "Cursed be he that lieth with his sister, the daughter of his father, or the daughter of his mother. And all the people shall say, Amen." Though only CHRIST lived a perfect and sinless life, it is clear that Abraham loved GOD and strove to do what is right. Deuteronomy 11:1 even repeats this for others to live by as it says "Therefore thou shalt love the LORD thy God, and keep his charge, and his statutes, and his judgments, and his commandments, alway."
6 And Isaac dwelt in Gerar:
7 And the men of the place asked him of his wife; and he said, She is my sister: for he feared to say, She is my wife; lest, said he, the men of the place should kill me for Rebekah; because she was fair to look upon.
If you're familiar with this book of Genesis, then you'll realize that Isaac did the same thing as his dad, Abraham, and claimed that his wife was his sister, out of fear that he may be killed, and clearly when people read this, they know that Rebekah was not Isaac's literal sister, but for some reason think differently when it comes to Abraham who did the same thing.
8 And it came to pass, when he had been there a long time, that Abimelech king of the Philistines looked out at a window, and saw, and, behold, Isaac was sporting with Rebekah his wife.
9 And Abimelech called Isaac, and said, Behold, of a surety she is thy wife; and how saidst thou, She is my sister? And Isaac said unto him, Because I said, Lest I die for her.
Now to recap what we've went over, let's go back to Genesis 20.
2 And the LORD appeared unto him, and said, Go not down into Egypt; dwell in the land which I shall tell thee of:
3 sojourn in this land, and I will be with thee, and will bless thee; for unto thee, and unto thy seed, I will give all these countries, and I will perform the oath which I sware unto Abraham thy father;
4 and I will make thy seed to multiply as the stars of heaven, and will give unto thy seed all these countries; and in thy seed shall all the nations of the earth be blessed;
5 Because that Abraham obeyed my voice, and kept my charge, my commandments, my statutes, and my laws.
Here we have documentation that Abraham obeyed GOD, and kept his charge, commandments, statutes, and laws. This word "commandments" is "mitsvâh" in the Hebrew, which is even the same word used for the Commandments that GOD gave to Moses. GOD even tells us in Deuteronomy 28, starting in verse 15, of all the curses that would come upon the people who did not keep all of HIS commandments, and as we can see, Abraham kept them by obeying GOD and striving to do what is right, as well as many of Adam's descendants, which means they would have known right from wrong, righteousness from unrighteousness, sin from non-sin, and again as mentioned earlier, GOD says in Deuteronomy 27:22, GOD says "Cursed be he that lieth with his sister, the daughter of his father, or the daughter of his mother. And all the people shall say, Amen." Though only CHRIST lived a perfect and sinless life, it is clear that Abraham loved GOD and strove to do what is right. Deuteronomy 11:1 even repeats this for others to live by as it says "Therefore thou shalt love the LORD thy God, and keep his charge, and his statutes, and his judgments, and his commandments, alway."
6 And Isaac dwelt in Gerar:
7 And the men of the place asked him of his wife; and he said, She is my sister: for he feared to say, She is my wife; lest, said he, the men of the place should kill me for Rebekah; because she was fair to look upon.
If you're familiar with this book of Genesis, then you'll realize that Isaac did the same thing as his dad, Abraham, and claimed that his wife was his sister, out of fear that he may be killed, and clearly when people read this, they know that Rebekah was not Isaac's literal sister, but for some reason think differently when it comes to Abraham who did the same thing.
8 And it came to pass, when he had been there a long time, that Abimelech king of the Philistines looked out at a window, and saw, and, behold, Isaac was sporting with Rebekah his wife.
9 And Abimelech called Isaac, and said, Behold, of a surety she is thy wife; and how saidst thou, She is my sister? And Isaac said unto him, Because I said, Lest I die for her.
Now to recap what we've went over, let's go back to Genesis 20.
Genesis 20
1 And Abraham journeyed from thence toward the south country, and dwelled between Kadesh and Shur, and sojourned in Gerar.
2 And Abraham said of Sarah his wife, She is my sister: and Abimelech king of Gerar sent, and took Sarah.
3 But God came to Abimelech in a dream by night, and said to him, Behold, thou art but a dead man, for the woman which thou hast taken; for she is a man’s wife.
4 But Abimelech had not come near her: and he said, Lord, wilt thou slay also a righteous nation?
5 Said he not unto me, She is my sister? and she, even she herself said, He is my brother: in the integrity of my heart and innocency of my hands have I done this.
6 And God said unto him in a dream, Yea, I know that thou didst this in the integrity of thy heart; for I also withheld thee from sinning against me: therefore suffered I thee not to touch her.
7 Now therefore restore the man his wife; for he is a prophet, and he shall pray for thee, and thou shalt live: and if thou restore her not, know thou that thou shalt surely die, thou, and all that are thine.
8 Therefore Abimelech rose early in the morning, and called all his servants, and told all these things in their ears: and the men were sore afraid.
9 Then Abimelech called Abraham, and said unto him, What hast thou done unto us? and what have I offended thee, that thou hast brought on me and on my kingdom a great sin? thou hast done deeds unto me that ought not to be done.
10 And Abimelech said unto Abraham, What sawest thou, that thou hast done this thing?
11 And Abraham said, Because I thought, Surely the fear of God is not in this place; and they will slay me for my wife’s sake.
12 And yet indeed she is my sister; she is the daughter of my father, but not the daughter of my mother; and she became my wife.
So here we see, Abraham admits with his own mouth that indeed Sarah is his sister; the daughter of his father, but not the daughter of his mother... but as we have seen numerous examples above, with terms such as "brother", "father", and "sister", they do not always insist one's literal brother, sister, or father, but can simply refer to kinship or someone related through a forefather, or related on the father's side, or simply someone from the same tribe, as in Deuteronomy 15:12, Numbers 18:2, as you can check out for yourself in the Hebrew. Besides the examples above though, in Genesis 11 it is written that Abraham's father, Terah, had three children (Abram/Abraham, Nahor, and Haran). Sarah is never mentioned as being his daughter. Also, as for other descendants of Adam that had other children, it is typically mentioned in Scripture that they had other "sons and daughters", as in Genesis 5:4, 5:7, 5:10, 5:13, 5:16, 5:19, 5:22, 5:26, 5:30, Genesis 11:11, 11:13, 11:15, 11:17, 11:19, 11:21, 11:23, 11:25, but in the case of Terah (Abraham's father), the very next generation after Nahor (11:25) it is never mentioned that he had other sons and daughters, only that he had three kids, Abraham, Nahor, and Haran. In Genesis 11:31, it is written "And Terah took Abram his son, and Lot the son of Haran his son’s son, and Sarai his daughter in law, his son Abram’s wife; and they went forth with them from Ur of the Chaldees, to go into the land of Canaan; and they came unto Haran, and dwelt there." If Sarai/Sarah was Abraham's sister, surely it would have been written, "And Terah took Abram his son, and Lot the son of Haran his son's son, and Sarai his daughter, his son Abram's wife..." but it is not. Notice the prevailing theme of the verse is how everyone is related to Terah; we already know Abram/Abraham was the son of Terah from Genesis 11:27, and that Haran fathered Lot from that same passage, along with Haran being the son of Terah from there as well. So why repeat it? Because we are supposed to take the phrase "and Sarai his daughter in law, his son Abrams wife." literally. Abraham even goes on to say in the next verse [see below]:
13 And it came to pass, when God caused me to wander from my father’s house, that I said unto her, This is thy kindness which thou shalt shew unto me; at every place whither we shall come, say of me, He is my brother.
Again, his intentions with this was so no one would kill him in order to obtain his wife, the same thing Isaac did with Rebekah his wife.
14 And Abimelech took sheep, and oxen, and menservants, and womenservants, and gave them unto Abraham, and restored him Sarah his wife.
15 And Abimelech said, Behold, my land is before thee: dwell where it pleaseth thee.
16 And unto Sarah he said, Behold, I have given thy brother a thousand pieces of silver: behold, he is to thee a covering of the eyes, unto all that are with thee, and with all other: thus she was reproved.
17 So Abraham prayed unto God: and God healed Abimelech, and his wife, and his maidservants; and they bare children.
18 For the LORD had fast closed up all the wombs of the house of Abimelech, because of Sarah Abraham’s wife.
Remember, Terah's dad (Abraham's grandpa) was also named Nahor, and again as it is written in Genesis 11:25, he begat other sons and daughters. So if you break the generations down [specifically the last 3 before Abraham], we'll see:
2 And Abraham said of Sarah his wife, She is my sister: and Abimelech king of Gerar sent, and took Sarah.
3 But God came to Abimelech in a dream by night, and said to him, Behold, thou art but a dead man, for the woman which thou hast taken; for she is a man’s wife.
4 But Abimelech had not come near her: and he said, Lord, wilt thou slay also a righteous nation?
5 Said he not unto me, She is my sister? and she, even she herself said, He is my brother: in the integrity of my heart and innocency of my hands have I done this.
6 And God said unto him in a dream, Yea, I know that thou didst this in the integrity of thy heart; for I also withheld thee from sinning against me: therefore suffered I thee not to touch her.
7 Now therefore restore the man his wife; for he is a prophet, and he shall pray for thee, and thou shalt live: and if thou restore her not, know thou that thou shalt surely die, thou, and all that are thine.
8 Therefore Abimelech rose early in the morning, and called all his servants, and told all these things in their ears: and the men were sore afraid.
9 Then Abimelech called Abraham, and said unto him, What hast thou done unto us? and what have I offended thee, that thou hast brought on me and on my kingdom a great sin? thou hast done deeds unto me that ought not to be done.
10 And Abimelech said unto Abraham, What sawest thou, that thou hast done this thing?
11 And Abraham said, Because I thought, Surely the fear of God is not in this place; and they will slay me for my wife’s sake.
12 And yet indeed she is my sister; she is the daughter of my father, but not the daughter of my mother; and she became my wife.
So here we see, Abraham admits with his own mouth that indeed Sarah is his sister; the daughter of his father, but not the daughter of his mother... but as we have seen numerous examples above, with terms such as "brother", "father", and "sister", they do not always insist one's literal brother, sister, or father, but can simply refer to kinship or someone related through a forefather, or related on the father's side, or simply someone from the same tribe, as in Deuteronomy 15:12, Numbers 18:2, as you can check out for yourself in the Hebrew. Besides the examples above though, in Genesis 11 it is written that Abraham's father, Terah, had three children (Abram/Abraham, Nahor, and Haran). Sarah is never mentioned as being his daughter. Also, as for other descendants of Adam that had other children, it is typically mentioned in Scripture that they had other "sons and daughters", as in Genesis 5:4, 5:7, 5:10, 5:13, 5:16, 5:19, 5:22, 5:26, 5:30, Genesis 11:11, 11:13, 11:15, 11:17, 11:19, 11:21, 11:23, 11:25, but in the case of Terah (Abraham's father), the very next generation after Nahor (11:25) it is never mentioned that he had other sons and daughters, only that he had three kids, Abraham, Nahor, and Haran. In Genesis 11:31, it is written "And Terah took Abram his son, and Lot the son of Haran his son’s son, and Sarai his daughter in law, his son Abram’s wife; and they went forth with them from Ur of the Chaldees, to go into the land of Canaan; and they came unto Haran, and dwelt there." If Sarai/Sarah was Abraham's sister, surely it would have been written, "And Terah took Abram his son, and Lot the son of Haran his son's son, and Sarai his daughter, his son Abram's wife..." but it is not. Notice the prevailing theme of the verse is how everyone is related to Terah; we already know Abram/Abraham was the son of Terah from Genesis 11:27, and that Haran fathered Lot from that same passage, along with Haran being the son of Terah from there as well. So why repeat it? Because we are supposed to take the phrase "and Sarai his daughter in law, his son Abrams wife." literally. Abraham even goes on to say in the next verse [see below]:
13 And it came to pass, when God caused me to wander from my father’s house, that I said unto her, This is thy kindness which thou shalt shew unto me; at every place whither we shall come, say of me, He is my brother.
Again, his intentions with this was so no one would kill him in order to obtain his wife, the same thing Isaac did with Rebekah his wife.
14 And Abimelech took sheep, and oxen, and menservants, and womenservants, and gave them unto Abraham, and restored him Sarah his wife.
15 And Abimelech said, Behold, my land is before thee: dwell where it pleaseth thee.
16 And unto Sarah he said, Behold, I have given thy brother a thousand pieces of silver: behold, he is to thee a covering of the eyes, unto all that are with thee, and with all other: thus she was reproved.
17 So Abraham prayed unto God: and God healed Abimelech, and his wife, and his maidservants; and they bare children.
18 For the LORD had fast closed up all the wombs of the house of Abimelech, because of Sarah Abraham’s wife.
Remember, Terah's dad (Abraham's grandpa) was also named Nahor, and again as it is written in Genesis 11:25, he begat other sons and daughters. So if you break the generations down [specifically the last 3 before Abraham], we'll see:
Again, it is NOT written that Terah had other "sons and daughters" and with what we have been given, Genesis 20:12 simply can mean that Sarah and Abraham shared a forefather on Abraham's dad's side, which means they simply could have been cousins, whether that be first, second, third, first once removed, second once removed, third once removed, etc., as Isaac and Rebekah were, which does NOT break any of the incest laws given in the Torah (i.e. law of Moses/under Moses), written in Leviticus 18. Again, it should be noted that in the original languages of the Bible, in which our English KJV is translated from, there are no words for "great-grandfather", "grandfather", "grandson", nor even "cousin" as far as the Old Testament goes, which means words like "sister" and "brother" could simply in some cases be referring to a cousin or distant cousin, or simply someone of the same tribe/race, as in Exodus 2:11-15, when Moses killed an Egyptian out of defense, who was hurting one of the people from Moses' race (the Hebrews).
Things To Consider:
If Abraham and Sarah were literal half-siblings, explain why it is never written that Terah had other "sons and daughters" when literally everyone before him in his genealogy, from the same chapter, it is written for them. Explain why Genesis 26:5 says "...Abraham obeyed my voice, and kept my charge, my commandments, my statutes, and my laws." if Abraham had committed such a sin as incest (a type of fornication). Explain why Abraham was greatly blessed by GOD when Scripture says in Deuteronomy 27:22 "Cursed be he that lieth with his sister, the daughter of his father, or the daughter of his mother. And all the people shall say, Amen." Surely if Abraham had done such a thing, then the Israelites would have definitely questioned Moses and complained about it, and tried to make justification for incest, by arguing that if Abraham could do it and it wasn't a sin, then surely they could too without consequences, but this is never the case.